ESCAPE VELOCITY: The velocity required to achieve orbit about a planet whereby the centripedal force pushing an object away fro the planet equals the gravitational force pulling an object toward the planet.

GRAVITY ASSIST: Gravity assist, also known as planetary swingby, uses a planet's gravity encountered encountered on a space trajectory to accelerate the payload's velocity toward the ultimate planetary destination. The technique is compared to a game of interplanetary billiards...a spacecraft's path is altered by diving close to the planet so that the planet's gravity can slingshot the spacecraft to a more distant planet.

HOHMANN TRAJECTORY (HOHMANN TRANSFER ORBIT): This is the most energy efficient route between the planets Discovered by a German engineer, Walter Hohmann in 1925, a Hohmann Trajectory launch point is on the launch planet orbit and is directly opposite the destination point on the destination planet orbit.